Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia
Legionella pneumophila is a facultative intracellular Gram-negative bacterium, which is a major causative agent of Legionnaires’ disease. In the environment, this bacterium survives in free-living protists such as amoebae and Tetrahymena. The association of L. pneumophila and protists leads to the r...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2018-04-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/article/10.3389/fmicb.2018.00800/full |
| _version_ | 1818143111671447552 |
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| author | Takashi Nishida Naho Hara Kenta Watanabe Takashi Shimizu Masahiro Fujishima Masahiro Fujishima Masahisa Watarai |
| author_facet | Takashi Nishida Naho Hara Kenta Watanabe Takashi Shimizu Masahiro Fujishima Masahiro Fujishima Masahisa Watarai |
| author_sort | Takashi Nishida |
| collection | DOAJ |
| description | Legionella pneumophila is a facultative intracellular Gram-negative bacterium, which is a major causative agent of Legionnaires’ disease. In the environment, this bacterium survives in free-living protists such as amoebae and Tetrahymena. The association of L. pneumophila and protists leads to the replication and spread of this bacterium. Thus, from a public health perspective, their association can enhance the risk of L. pneumophila infection for humans. Paramecium spp. are candidates of natural hosts of L. pneumophila, but their detailed relationships remain unclear. In the present study, we used an environmental strain, L. pneumophila Ofk308 (Ofk308) and Paramecium tetraurelia st110-1a to reveal the relationship between L. pneumophila and Paramecium spp. Ofk308 was cytotoxic to P. tetraurelia in an infection-dependent manner. We focused on TolC, a component of the type I secretion system, which is a virulence factor of L. pneumophila toward protists and found that cytotoxicity was dependent on TolC but not on other T1SS components. Further, the number of bacteria in P. tetraurelia was not associated with cytotoxicity and TolC was not involved in the mechanism of resistance against the digestion of P. tetraurelia in Ofk308. We used a LysoTracker to evaluate the maturation process of P. tetraurelia phagosomes containing Ofk308. We found that there was no difference between Ofk308 and the tolC-deletion mutant. To assess the phagocytic activity of P. tetraurelia, Texas Red-conjugated dextran-uptake assays were performed. Ofk308 inhibited phagosome formation by P. tetraurelia through a TolC-dependent mechanism. Further, we evaluated the excretion of Legionella-containing vacuoles from P. tetraurelia. We found that P. tetraurelia failed to excrete undigested Ofk308 and that Ofk308 remained within cells through a TolC-dependent mechanism. Our results suggest that TolC is essential for L. pneumophila to remain within Paramecium cells and to show cytotoxicity. Because of the high mobility and high cell division rate of Paramecium spp., living with Paramecium spp. would be beneficial for L. pneumophila to expand its habitat. To control Legionaries’ disease, understanding the ecology of L. pneumophila in the environment is essential. |
| first_indexed | 2024-12-11T11:26:29Z |
| format | Article |
| id | doaj.art-a583f65eb60d43f19a9135ed3f709dbf |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-11T11:26:29Z |
| publishDate | 2018-04-01 |
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| series | Frontiers in Microbiology |
| spelling | doaj.art-a583f65eb60d43f19a9135ed3f709dbf2022-12-22T01:08:59ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2018-04-01910.3389/fmicb.2018.00800352712Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraureliaTakashi Nishida0Naho Hara1Kenta Watanabe2Takashi Shimizu3Masahiro Fujishima4Masahiro Fujishima5Masahisa Watarai6The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, JapanThe United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, JapanThe United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, JapanThe United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, JapanDepartment of Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, JapanNational BioResource Project, Japan Agency for Medical Research and Development, Tokyo, JapanThe United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, JapanLegionella pneumophila is a facultative intracellular Gram-negative bacterium, which is a major causative agent of Legionnaires’ disease. In the environment, this bacterium survives in free-living protists such as amoebae and Tetrahymena. The association of L. pneumophila and protists leads to the replication and spread of this bacterium. Thus, from a public health perspective, their association can enhance the risk of L. pneumophila infection for humans. Paramecium spp. are candidates of natural hosts of L. pneumophila, but their detailed relationships remain unclear. In the present study, we used an environmental strain, L. pneumophila Ofk308 (Ofk308) and Paramecium tetraurelia st110-1a to reveal the relationship between L. pneumophila and Paramecium spp. Ofk308 was cytotoxic to P. tetraurelia in an infection-dependent manner. We focused on TolC, a component of the type I secretion system, which is a virulence factor of L. pneumophila toward protists and found that cytotoxicity was dependent on TolC but not on other T1SS components. Further, the number of bacteria in P. tetraurelia was not associated with cytotoxicity and TolC was not involved in the mechanism of resistance against the digestion of P. tetraurelia in Ofk308. We used a LysoTracker to evaluate the maturation process of P. tetraurelia phagosomes containing Ofk308. We found that there was no difference between Ofk308 and the tolC-deletion mutant. To assess the phagocytic activity of P. tetraurelia, Texas Red-conjugated dextran-uptake assays were performed. Ofk308 inhibited phagosome formation by P. tetraurelia through a TolC-dependent mechanism. Further, we evaluated the excretion of Legionella-containing vacuoles from P. tetraurelia. We found that P. tetraurelia failed to excrete undigested Ofk308 and that Ofk308 remained within cells through a TolC-dependent mechanism. Our results suggest that TolC is essential for L. pneumophila to remain within Paramecium cells and to show cytotoxicity. Because of the high mobility and high cell division rate of Paramecium spp., living with Paramecium spp. would be beneficial for L. pneumophila to expand its habitat. To control Legionaries’ disease, understanding the ecology of L. pneumophila in the environment is essential.http://journal.frontiersin.org/article/10.3389/fmicb.2018.00800/fullLegionella pneumophilaParameciumTolCcellular traffickingsymbiosis |
| spellingShingle | Takashi Nishida Naho Hara Kenta Watanabe Takashi Shimizu Masahiro Fujishima Masahiro Fujishima Masahisa Watarai Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia Frontiers in Microbiology Legionella pneumophila Paramecium TolC cellular trafficking symbiosis |
| title | Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia |
| title_full | Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia |
| title_fullStr | Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia |
| title_full_unstemmed | Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia |
| title_short | Crucial Role of Legionella pneumophila TolC in the Inhibition of Cellular Trafficking in the Protistan Host Paramecium tetraurelia |
| title_sort | crucial role of legionella pneumophila tolc in the inhibition of cellular trafficking in the protistan host paramecium tetraurelia |
| topic | Legionella pneumophila Paramecium TolC cellular trafficking symbiosis |
| url | http://journal.frontiersin.org/article/10.3389/fmicb.2018.00800/full |
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